Transfer device

ABSTRACT

A device for transferring workpieces sequentially along groups of work stations, successive groups having different index spacing. One or more transfer bars extend through each group, the transfer bars of one group being reciprocated by a fluid motor with a fixed stroke. The motion is transmitted to the transfer bars of other groups in tandem with the first by mechanisms which compensate for the differences in index distance between the stations of successive groups. The transfer drive compensating mechanism between each group of stations comprises an arm pivoted at its inner end to a vertically slidable support and at its outer end to the transfer bar having the greater movement of the two successive bars. An intermediate portion of the arm is connected by links to the other set of transfer bars.

United States Patent Pfrommer et al.

' 154] TRANSFER DEVICE [72] Inventors: Fritz Pfrommer, Neckarhausen,

Germany; Bansal Suresh, Warren, Mich.

[73] Assignee: The Cross Company, Fraser, Mich.

[22] Filed: April 26, 1971 [21] Appl. No.: 137,136

[52] US. Cl. ..l98/19, 198/76, 198/219, 7 74/1 10 [51] Int. Cl ..B65g 37/00 [58] FieldofSearch ..l98/l9,76,82,2l9;74/110 [15] 3,685,630 51 Aug. 22, 1972 Primary ExaminerRichard E. Aegerter Assistant ExaminerH. S. Lane Attorney-Harness, Dickey & Pierce [57] ABSTRACT A device for transferring workpieces sequentially along groups of work stations, successive groups having different index spacing. One or more transfer bars extend through each group, the transfer bars of one group being reciprocated by a fluid motor with a fixed stroke. The motion is transmitted to the transfer bars of other groups in tandem with the first by mechanisms which compensate for the differences in index distance between the stations of successive groups. The transfer d'rive compensating mechanism between each group of stations comprises an arm pivoted at its inner end to a vertically slidable support and at its outer end to the transfer bar having the greater movement of the two successive bars. An intermediate portion of the arm is connected by links to the other set of transfer bars.

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m mx PATENIEDnusez an SHEET 8 BF 7 TRANSFER DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to transfer devices used to move workpieces, or pallets carrying workpieces, along a series of work and/or idle stations, so that the workpieces may be automatically machined, assembled or otherwise processed or acted upon. Typically, the workpieces or pallets ride on guide rails and are advanced by one or more transfer bars extending in tandem through groups of stations. As shown in FIGS. 1 to 3 of US. Pat. No. 3,361,250, the transfer bar may be reciprocable along its axis and oscillatable angularly about its axis to bring it alternately into and out of engagement with the parts being transferred. Another manner of arranging the transfer bars is shown in FIGS. 1 1 to 14 of said patent, the bars being actuatable vertically as well as longitudinally so that they lift and carry the parts from one station to the next. A third arrangement of the transfer bars is shown in US. Pat. No. 3,155,217, the bars in this case being movable vertically but only enough to engage the part or pallet without lifting it off the guide rails.

The present invention pertains particularly to instances where there are several groups of work stations along the entire path of movement of the workpieces, the indexing distance between stations in one group being different than in the adjacent group. The invention is also particularly concerned with the transfer of relatively heavy workpieces such as engine blocks, which involve high inertial and gravitational forces.

2. Description of the Prior Art In the past it has been necessary to provide relatively complex, cumbersome and expensive apparatus for imparting different indexing movements to the transfer bars at adjacent groups of stations. An example of a prior construction for achieving differential movement between adjacent transfer bars is shown in FIGS. 1 l to 14 of the aforesaid US. Pat. No. 3,361,250.

BRIEF SUMMARY OF THE INVENTION According to the invention, a transfer drive compensating mechanism is placed between adjacent transfer bars which are to be actuated at different indexing distances. One of these transfer bars will be driven from a power source, either directly or remotely, and the second will be driven from the first through this compensating mechanism.

The mechanism itself comprises an arm the inner end of which is pivoted to a slide mounted for free vertical movement on a post secured to the machine base. The outer end of the arm is pivotally connected to the transfer bar having the greater index travel. An intermediate portion of the arm is connected by a pivoted link to the transfer bar having the lesser index travel. In this manner, the horizontal movements of the two transfer bars in tandem will be different for each rocking movement of the arm about its inner pivot. The arrangement is such that vertical lifting and lowering movement of the transfer bars in unison will be permitted in installations where such movement is used to transfer the parts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary diagrammatic plan view of a typical installation which may use the transfer device of this invention, namely a line of machine tools for automatically machining engine blocks;

FIG. 2 is a fragmentary diagrammatic plan view of the transfer bars at the various groups of stations together with their actuating means and the locations of the transfer drive compensating mechanisms of this invention;

FIG. 3 is a fragmentary diagrammatic elevational view at one station showing the manner in which the transfer bars are raised and lowered;

FIG. 4 is an enlarged cross-sectional view in elevation showing the transfer bars in one group of stations surmounted by a parts nest or support;

FIG. 5 is an enlarged diagrammatic plan view of two adjacent stations between which the engine blocks are reoriented, thus necessitating a different index distance between stations;

FIG. 6 is an elevational view of the stations of FIG. 5 showing the locating pins and rest pads for the parts at the two stations, taken in the direction of the arrow 6 of FIG. 5;

FIG. 7 is a side elevational view of the transfer drive compensating mechanism disposed between the two stations illustrated in FIGS. 5 and 6, taken in the direction of the arrow 7 of FIGS. 2 and 5;

FIG. 8 is a front elevational view, partly sectioned, of the mechanism of FIG. 7 taken in the direction of the arrow 8 thereof;

FIG. 9A is a schematic view of the mechanism shown in its FIG. 7 position;

FIG. 9B is a view similar to FIG. 9A but showing the mechanism in its raised position prior to delivery of parts to the next station;

FIG. 9C is a view similar to FIGS. 9A and 9B but showing the position of the mechanism after the parts have been delivered to the next stations but before they have been lowered;

FIG. 9D is a view similar to FIGS. 9A, 9B and 9C but showing the position of the mechanism after the parts have been lowered at their new stations; and

FIG. 10 is a side elevational view of another transfer drive compensating mechanism taken in the direction of the arrow 10 of FIG. 2 leading from the group of stations with relatively short index travel to one with longer index travel.

DESCRIPTION OF THE PREFERRED EMBODIMENT A typical machine tool line incorporating the invention is indicated generally at 101 in FIG. 1. The line is shown as having 38 stations through which the workpieces, such as engine blocks, are progressively transferred. At some of these stations the workpieces are operated upon by machine tools such as those indicated by the letters A, B, etc. Other stations are considered to be idle stations at which the workpieces are held in order to maintain a properly timed relationship with the others during their sequential movement.

The stations may be considered as divided into sections depending on the index distance between adjacent stations. In the present example, three sections are shown. Section 1 consists of stations 1 to 6 and has a relatively short index distance between adjacent stations, this distance being constant throughout the section. Section 2 comprising stations 7 through 18 has a greater index distance whereas Section 3 consisting of stations 19 through 38 again has a shorter index distance between stations.

FIG. 2 indicates three sets of transfer bars. The transfer bars in Section 1 are indicated at 102 and 103, those in Section 2 at 104 and 105 and the bars in Section 3 at 106 and 107. Each pair of bars are in spaced parallel relation and extend through the work stations of their section. In the illustrated embodiment, the bars are of the lift-and-carry type, although it will be understood that the present invention is applicable to other types of transfer bars. The lift-and-carry" arrangement is shown particularly in FIGS. 1 I through 14 of the aforementioned US. Pat. No. 3,361,250. All the sets of transfer bars are simultaneously reciprocable in their longitudinal direction by a fluid motor 108, shown in this instance as being connected to the discharge ends of transfer bars 106 and 107 by a piston rod 109. Extension of this rod will move all the transfer bars to the left and retraction will move them to the right, adjacent pairs of bars being interconnected by the novel transfer drive compensating mechanism of this invention. Two such compensating mechanisms are indicated schematically in dot-dash lines in FIG. 2 by the reference numerals 111 and 112. Mechanism 111 will transmit the motion from bars 106 and 107 to bars 104 and 105 whereas mechanism 112 will transmit the motion from the latter transfer bars to bars 102 and 103.

Each pair of transfer bars, such as bars 102 and 103, are illustrated in FIG. 4 as carrying parts nests or supports 113. These supports are provided with pins 114 for engaging the workpieces 115 (see FIG. 6) at predetermined locations in order to lift the workpieces from one work station and carry them to the next.

The means for lifting and lowering the transfer bars comprises a plurality of arms 116 (FIG. 3) pivoted at spaced points along machine 101. The outer ends of these arms have rollers 117 which engage the transfer bars. The arms are rocked by one or more fluid motors 118, a piston rod 119 of which is connected to an actuating rod 121. This rod is pivotally connected to arms 116 at 122. Movement of rod 121 to the left from its FIG. 3 position will permit its associated transfer bar to be lowered under its own weight and that of the workpieces which it supports.

As described more fully in the aforesaid US. Pat. NO. 3,361,250, a cycle for advance of the workpieces will consist firstly in lifting transfer bars so as to elevate the workpieces from their stations, followed by a retracting movement of piston rod 109 which advances all of the workpieces as carried by the transfer bars to their next stations. Extension of piston rod 119 will then lower the transfer bars until the workpieces rest at their next stations. While in their lowered positions, in which the transfer bars are disengaged from the workpieces, piston rod 109 will be extended to return the transfer bars to their previous positions in readiness for lifting the succeeding workpieces.

FIGS. and 6 show the manner in which workpieces 1 are located and supported at work stations, the two stations shown being stations 18 and 19. The stations are provided with rest pads 123 and fixture pins 124 carried by a base 125. Workpieces 115 will be located by pins 124 and supported by pads 123, a conventional clamping means (not shown) being used to secure the parts in position at the stations. The workpieces are provided with holes 126 for receiving transfer bar pins 1 14 when being lifted from their stations.

It will be noted that in being transferred from station 18 to station 19, each workpiece 115 is rotated by means not shown. In the present instance, the workpieces are illustrated as being engine blocks of rectangular shape and at station 18 the long axis of the workpiece is in the direction of index travel, whereas at station 19 the long axis is at right angles to the direction of travel. For this reason the index distance in Section 3 is shorter than in Section 2. Similarly, the engine blocks will be rotated from a transverse to a longitudinal position when moving from-station 6 to 7 and therefore the index distance in Section 2 will be greater than in Section 1.

F IGS. 7 and 8 illustrate the transfer drive compensating mechanism 111 disposed between stations 18 and 19 which actually transmits'the motion from transfer bars 106 and 107 to transfer bars 104 and 105, although the workpieces are travelling from station 18 to station 19. It should be kept in mind that in FIG. 7 the parts flow is from right to left whereas the flow in FIGS. 1, 2 and 3 is from left to right.

Mechanism 1 11 comprises an arm 127 having a pair of forked lower extensions 128 and 129. These extensions are pivotally connected at 131 to a pair of slides 132 mounted for free vertical movement on posts 133 fixed to the machine base indicated in phantom lines at 134. The outer end of arm 127 is pivoted at 135 to transfer bars 104 and 105. As illustrated, this connection is by means of a parts nest or support 136, but the connection could be by means of a suitable bracket. An intermediate portion of arm 127 is connected to transfer bars 106 and 107 by a pair of links 137, these links being pivoted at 138 to arm 127 and at 139 to transfer bars 106 and 107.

FIGS. 9A through 9D show in sequence the positions of the parts during operation. Starting from the position of FIG. 9A, when it is desired to transfer the parts to the next stations, arms 116 will be swung counterclockwise by motor 118. This will lift all the transfer bars including bars 104 through 107. Note that guides 132 will rise on posts 133 (FIG. 9B). Arm 127 will rise along with links 137. The parts having been lifted by the transfer bars, piston rod 109 of motor 108 will be retracted. The transfer bars will travel on rollers 117, guides 132 dipping and then rising to accommodate the motion of arm 127. Note that while transfer bars 104 and connected to the outer end of arm 127 will travel a relatively great distance, transfer bars 106 and 107 will be moved a substantially shorter distance because they are connected to an intermediate portion ofthe arm (FIG. 9C).

When the parts have reached their next stations, arms 116 will be swung clockwise from their FIG. 9C position, lowering the transfer bars and the compensating mechanism to the FIG. 9D position. The parts will then be mounted at their new stations and the transfer bars lowered to retract their work supports from the workpieces. Extension of piston rod 109 of motor 108 will then retract all of the transfer bars, arm 127 returning to its FIG. 9A position. Again, the distance traveled by transfer bars 104 and 105 will be substantially greater than that traveled by bars 106 and 107.

FIG. 10 is a view similar to FIG. 7' but showing the compensating mechanism 1 12 located between stations 5 and 6. This mechanism transmits motion from transfer bars 104 and 105 to transfer bars .102 and 103. The latter transfer bars are in Section 1 of the assembly and move workpieces toward Section 2 which has transfer bars 104 and 105. As will be recalled, the index distance in Section 1 is substantially less than that in Section 2. It should be kept in mind that, as in FIG. 7, the parts flow is from right to left.

The construction of compensating mechanism 1 12 is similar to that of mechanism 1 11. The mechanism comprises a post 141 secured to frame portion 142 of the machine and carries a vertically movable slide'143. The lower end of a forked arm 144 is pivoted at 145 to slide 143. The outer end of arm 144 is pivoted at 146 to a bracket 147 secured to transfer bars 104 and 105. An intermediate portion of arm 144 is connected by links 148 to transfer bars 102 and 103. Links 148 are pivoted to arm 144 at 149 and to transfer bars 102 and 103 at 151.

The action of mechanism 112 will be the same as that of mechanism 1 11 and therefore need not be described in detail. It should be noted that the relatively long stroke imparted to transfer bars 104 and 105 by mechanism 111 will be transmitted to transfer bars 102 and 103 as a relatively short stroke because of the geometry of mechanism 112. As before, the parts will be enabled by slide 143 to rise and fall vertically as the transfer bars are raised and lowered by arms 116.

What is claimed is:

1. In a workpiece transfer drive of the type having a plurality of reciprocable transfer bars in tandem, a transfer drive compensating mechanism between two transfer bars, said mechanism comprising an arm having inner and outer ends, a pivotal support for the inner end of said arm, means guiding said pivotal support for free movement transverse to the direction of reciprocation of said transfer bars, an articulated connection between the outer end of said arm and one of said transfer bars, and a second articulated connection between an intermediate portion of said arm and the other transfer bar, whereby reciprocation of said first transfer bar through a given index distance will be accompanied by reciprocation of the other transfer bar a substantially lesser distance.

2. The combination according to claim 1, said first articulated connection comprising a pivoted connection, said second articulated connection comprising a link pivoted at one end to said arm and at the other end to said other transfer bar.

3. The combination according to claim 1, further provided with a second transfer drive compensating mechanism between said other transfer bar and a third transfer bar, said second compensating mechanism having an arm pivotally supported at its inner end by means guided for free movement transverse to the direction of reciprocation of the transfer bars, an articulated connection between the outer end of said arm and said third transfer bar, and a second articulated connection between an intermediate portion of said d 'd f b T. llie orgliiii altibii gc c or lng to claim 3, all of said transfer bars being further provided with means for moving them in unison transverse to the reciprocating direction of the transfer bars, all of said articulated connections being so constructed as to permit said lastmentioned movement of the transfer bars.

5. The combination according to claim 4, the first articulated connection of each of said two compensating mechanisms comprising a pivoted connection, the second articulated connection comprising a link pivoted at one end to the arm and at the other end to the transfer bar.

6. In a transfer drive of the type having first and second horizontally reciprocable transfer bar means in tandem and means for raising and lowering said transfer bar means in unison, a transfer drive compensating mechanism between said transfer bar means comprising an arm having inner and outer ends, means pivotally supporting the inner end of said arm, means guiding said pivotal supporting means for free vertical movement, a pivotal connection between the outer end of said arm and said first transfer bar means, link means having one end pivoted to an intermediate portion of said arm, and a pivotal connection between the other end of said link means and said second transfer bar means, whereby horizontal reciprocation of said first transfer bar means through a predetermined index distance will be accompanied by reciprocation of the second transfer bar means a substantially lesser distance, and both transfer bar means may be raised and lowered in unison.

7. The combination according to claim 6, the inner end of said arm being forked, said pivotal supporting means comprising two slides connected to the forked end of the arm, said vertical guide means comprising two relatively fixed posts.

8. The combination according to claim 6, said first and second transfer bar means each comprising two transfer bars, the means for pivotally connecting said first transfer bar means to the arm comprising a bracket secured to the two transfer bars of said first transfer bar 

1. In a workpiece transfer drive of the type having a plurality of reciprocable transfer bars in tandem, a transfer drive compensating mechanism between two transfer bars, said mechanism comprising an arm having inner and outer ends, a pivotal support for the inner end of said arm, means guiding said pivotal support for free movement transverse to the direction of reciprocation of said transfer bars, an articulated connection between the outer end of said arm and one of said transfer bars, and a second articulated connection between an intermediate portion of said arm and the other transfer bar, whereby reciprocation of said first transfer bar through a given index distance will be accompanied by reciprocation of the other transfer bar a substantially lesser distance.
 2. The combination according to claim 1, said first articulated connection comprising a pivoted connection, said second articulated connection comprising a link pivoted at one end to said arm and at the other end to said other transfer bar.
 3. The combination according to claim 1, further provided with a second transfer drive compensating mechanism between said other transfer bar and a third transfer bar, said second compensating mechanism having an arm pivotally supported at its inner end by means guided for free movement transverse to the direction of reciprocation of the transfer bars, an articulated connection between the outer end of said arm and said third transfer bar, and a second articulated connection between an intermediate portion of said arm and said other transfer bar.
 4. The combination according to claim 3, all of said transfer bars being further provided with means for moving them in unison transverse to the reciprocating direction of the transfer bars, all of said articulated connections being so constructed as to permit said last-mentioned movement of the transfer bars.
 5. The combination according to claim 4, the first articulated connection of each of said two compensating mechanisms comprising a pivoted connection, the second articulated connection comprising a link pivoted at one end to the arm and at the other end to the transfer bar.
 6. In a transfer drive of the type having first and second horizontally reciprocable transfer bar means in tandem and means for raising and lowering said transfer bar means in unison, a transfer drive compensating mechanism between said transfer bar means comprising an arm having inner and outer ends, means pivotally supporting the inner end of said arm, means guiding said pivotal supporting means for free vertical movement, a pivotal connection between the outer end of said arm and said first transfer bar means, link means having one end pivoted to an intermediate portion of said arm, and a pivotal connection between the other end of said link means and said second transfer bar means, whereby horizontal reciprocation of said first transfer bar means through a predetermined index distance will be accompanied by reciprocation of the second transfer bar means a substantially lesser distance, and both transfer bar means may be raised and lowered in unison.
 7. The combination according to claim 6, the inner end of said arm being forked, said pivotal supporting means comprising two slides connected to the forked end of the arm, said vertical guide means comprising two relatively fixed posts.
 8. The combination according to claim 6, said first and second transfer bar means each comprising two transfer bars, the means for pivotally connecting said first transfer bar means to the arm comprising a bracket secured to the two transfer bars of said first transfer bar means and pivoted to said arm, said link means comprising two parallel links pivoted at one end to said arm anD at the other end to the two transfer bars of said second transfer bar means. 